Falls are the number-one cause of unintentional injury and second- largest cause of accidental death in the elderly. While a variety of sensory, motor, and cognitive deficits have been found to increase fall risk, basic differences in the motor control of movement between fallers and non-fallers remain poorly understood. We propose that an important yet largely unrecognized mechanism for falls in the elderly is a mismatch between actual and perceived motor abilities, leading to the planning of movements which inadvertently stress one's limits of postural stability. Accordingly, in the proposed research we will test the hypothesis that an exaggerated perception of postural limits represents a risk factor for falls in the elderly. To address this hypothesis, we will conduct a simple reaching experiment which requires subjects to frrst estimate how far they can reach horizontally (along a tape measure located at shoulder height), and then perform a maximum- reach task. The primary outcome variable will be the percent difference between predicted and actual reach distances. We will test two groups of elderly over the age of 70 years (with n=50 in each group): non- fallers (having one or no documented, unexplained falls within the past 12 months), and fallers (having two or more documented, unexplained falls within the past 12 months). To maximize the accuracy of fall history data, we will recruit from nursing homes and elderly day-cares which maintain detailed records of falls. A major advantage of our protocol is the ability to conduct testing at these various sites, rather than in a laboratory environment. Logistic regression will be used to assess the relative importance in determining fall risk of (1) accuracy in perceiving postural limits, (2) sensorimotor capacity (based on indices of strength, reaction time, balance, and visual acuity), (3) activity level, (4) fear of falling, and (5) indices of cognitive function and depression. Correlations between the above independant variables wil be examined to identify factors which influence perception of postural limits, and assess, for example, how perception of motor ability scales with actual motor ability. Regardless of whether we find that falleers exaggerate or underestimate their abilities, our results should have implications regarding the role of "postural awareness" therapies for the reduction of falls in the elderly. We also expect this project to provide important pilot data for further studies which will expore how movement planning and execution is affected by perception of postural limits, and how the accuracy of perceived postural limits is affected by specific neuro- degenerative processes.